Data recording and reproducing method for multi-layered optical disk system

ABSTRACT

A data recording and reproducing method for an optical disk data storage system to record data compressed at different data compression rate according to an operator&#39;s specification, and to reproduce the recorded data by decompressing. According to the operator&#39;s indication, the data is recorded at certain data compression rate in indicated area. The information of the data compression rate and the recorded area is stored as a table of contents (TOC) data. The TOC data is reproduced and stored in a memory after the optical disk is loaded. The recorded data is reproduced by selecting a decoding circuit to decompress the data. The decoding circuit is selected by referring the TOC data to identify data compression rate of the recorded data. Also the TOC data is referred to identify read-in and read-out region of the recorded data. The position of a pick-up when the data recording is started and ended, is recorded as the TOC data to provide random access capability for the data reproduction.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to an optical data recording andreproducing method. More specifically, this invention relates to anoptical disk recording and reproducing method which makes possible torecord data encoded by different encoding circuit at different datacompression rate and to reproduce the data.

[0003] 2. Description of the Prior Art

[0004] Initialized by the vast increase in information that needs to beprocessed, optical data storage system having become very importantsystem particularly because of their high storage density per area. Mostof the recent optical information storage systems rotating singleoptical disk are used on which the information is digitally stored inconcentric circular tracks in an ordered, predefined manner to allowchronological fast reading and fast random access to desired pits ofdata.

[0005] In order to accomplish even more storage capacity of optical disksystems for enormous information processing, such as video or picturecommunication like so called video-on-demand service, multiple disksystems have been proposed. An optical disk system equipped with two ormore data layers may in theory be accessed as different disks bychanging the focal point with moving lens. Example of this type ofstate-of-the-art include U.S. Pat. No. 5,202,875 issued Apr. 13, 1993 toRosen et al.; Japanese Published Application, 63-276732 published Nov.15, 1988 by Watanabe, et al.

[0006] Such a multiple disk recording and reading system is applied tovaried optical disk information storage systems. For example, a digitalvideo disk (DVD) system for home entertaining is one of the typicalapplication. The mentioned advantage of vast storage capacity maycontribute especially for video signal transmission. In order to recordthe video data efficiently onto the optical disk, a video datacompression technique is one of the key technologies. A standardizedvideo data compression rate has been proposed, which is called MPEG(Moving Picture Experts Group). However, for the home entertainingpurposes, a more flexible function is required. The ability to recorddata at different data compression rates and to reproduce the recordeddata, must be provided.

3. SUMMARY OF THE INVENTION

[0007] The present invention has for its object to provide amulti-layered optical disk recording and reproducing system which isable to record data encoded by different encoding circuits at differentdata compression rates and to reproduce the data by a selected decodingcircuit.

[0008] The object of the present invention can be achieved by an opticaldata recording and reproducing method, the recording method comprisingthe steps of: loading a multi-layered optical disk which has M datalayers (wherein M is an integer greater than 1), receiving an operator'ssignal to record data on an Nth data layer of the multi-layered opticaldisk at a certain data compression rate (wherein N is an integer greaterthan 1 and not greater than M), operating a routing circuit to transmitthe data to a determined encoding circuit in order to compress the dataat a predetermined data compression rate, recording the data onpredetermined position at the predetermined data compression rate, andrewriting table of contents (TOC) data to record data about the datacompression rate of the newly recorded data.

[0009] And the object of the present invention also can be achieved byan optical data recording and reproducing method, the reproducing methodcomprising the steps of: loading a multi-layered optical disk, which hasM data layers (wherein M is an integer greater than 1), reproducing atable of contents (TOC) data recorded in the multi-layered optical disk,storing the reproduced TOC data in a memory, receiving an operator'ssignal to reproduce selected data stored in the multi-layered opticaldisk, referring to the TOC data stored in the memory to identify thedata compression rate of the selected data, and operating a routingcircuit to transmit a readout signal of the selected data to thedetermined encoding circuit in order to decompress the selected data.

[0010] For a fuller understanding of the nature and advantages of thepresent invention, reference should be made to the following detaileddescription taken in conjunction with the accompanying drawings.

4. BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows a block diagram of an example of an optical datarecording and reproducing apparatus to which the present invention canbe applied;

[0012]FIG. 2 shows a flowchart for a description of an optical diskrecording method of the present invention; and

[0013]FIG. 3 shows a flowchart for a description of an optical diskreproducing method of the present invention.

5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Embodiments of the present invention will be explained withreference to the drawings.

[0015]FIG. 1 shows a block diagram of a first example of an optical datarecording and reproducing apparatus to which the present invention canbe applied. A digital video disk (DVD) 10 which has more than two datalayers is mounted on and secured by a turntable 11 to be rotated by aspindle motor 12. Encoded pits on the DVD 10 are read by a pickup 13which includes a laser diode, a focusing lens, a focusing lens actuator,a tracking actuator and a photo-detector. The movement of the pick-up 13is controlled by a focusing servo circuit 14 and a tracking servocircuit 15.

[0016] To reproduce data encoded on the DVD 10, the output signal fromthe pickup 13 is transmitted to an amplifier 16. According to a focusingerror signal, the focusing servo circuit 14 modulates the focusing lensactuator to move the focal point of the laser beam emitted from thelaser diode by moving the focusing lens, to access one of the data layerof the DVD 10. And according to a tracking error signal, the trackingservo circuit 15 modulates the tracking actuator to control position ofthe pickup 13. The spindle servo circuit 17 modulates the spindle motor12 in order to track linear velocity of the DVD 10.

[0017] The detected signal by the pick-up 13 is amplified by theamplifier 16. And the amplified signal is transmitted to a dataprocessing unit 18 which is composed of a routing switch 19, an MPEG-2decoder 20 and a ½ decoder 21. The MPEG-2 decoder 20 is a standardizeddata encoding or decoding circuit for a Digital Video Disk (DVD),provided in order to encode a data signal for recording on the disk andto decode the read out signal for signal processing. The ½ decoder 21 isa data encoding or decoding circuit provided to encode and compress theapplied data signal to half data rate of the standardized DVD format.Due to the data compression by the ½ decoder 21, the quality of the datamust be sacrificed in order to record longer data per recording area.However, it makes it possible to provide additional functionality andflexibility for the user. A set of TOC data encoded at a read-in regionof the DVD 10, must include the data indicative of the starting andending position of each data portion, and the data compression rate ofeach data. The TOC data is reproduced right after the DVD is loaded, andthen the each data reproduction is preceded by referring the TOC data.And the TOC data must be rewritten after new data is recorded.

[0018] The routing switch 19 is operated by a central processing unit(CPU) 22 according to the detected TOC data, which includes the dataindicating the compression rate of each data to determine theappropriate decoding circuit. The TOC data is also transmitted to aservo control circuit 23 which modulates the focusing servo circuit 14,the tracking servo circuit 15 and the spindle servo circuit 17. Theservo control circuit 23 modulates each servo circuit to access selecteddata according to the TOC data which indicates the data indicating thestarting and ending positions of each encoded data portion. Then thedecoded signal is transmitted to a signal processor 24 to transmit thereproduced data signal to any connected unit, such as a display systemor sound system. The CPU 22 is operated by an operation signal from akey operating unit 26 which transmits all operating signals input by anoperator. The CPU 22 also controls a display unit 25 to show theoperating status of the operator.

[0019] To record data onto the DVD 10, a portion of an input data signalis transmitted from the signal processor 24 to the chosen decoder in thedata processing unit according to the operator's command. The input datasignal is encoded by the selected decoder, then recorded by the pickup13 which is driven by the each servo circuit and the servo controlcircuit 23. After the new data is recorded on the DVD 10, the TOC datais rewritten to store the data indicating the position and datacompression rate of the newly recorded data.

[0020] In addition, by storing the data of read-in and readout positionof the all recorded data as TOC data, a capability of quick randomaccess to any data portion is provided for the data reproductionprocess. For example, in order to reproduce one data and another datacontinuously, the pick-up head can rapidly switch access from readoutregion of the first data to the read-in region of the second data, ifdata as to all of the read-in region's position is stored and recordedin the TOC data. In the prior art system, all of the read-in region ofthe data between the first and second data must be counted by detectingthe readout signal. For example, in order to reproduce both a 4^(th)data element and a 14^(th) data element recorded on the disk, thepick-up must detect and count ten read-in regions of the data between4^(th) and 14^(th) data regions by moving the pick-up all over the disk.The present invention can provide the advantage of reproducing the datacontinuously without timelag. The advantage may contribute remarkably tothe multi-layered optical disk reading systems which is equipped withmore than two data layers.

[0021]FIG. 2 shows a flowchart of operation processing in a centralprocessing unit (CPU), while recording data onto one data layer of amulti-layered optical disk. After a multi-layered optical disk which hasM data layers (wherein M is an integer greater than 1) is loaded, theCPU receives an operator's signal to record data on the Nth data layerof multi-layered optical disk (wherein N is an integer greater than 1and not greater than M). The CPU operates a servo control circuit todispose a pick-up in order to access read-in region of the data to berecorded (Step 1:S1). According to the operator's selection of a datacompression rate (S2), the CPU operates a routing circuit to transmitthe data the determined encoding circuit in order to compress the dataat the selected data compression rate (S3). The CPU operates a servocontrol circuit to record the data on a predetermined position at thepredetermined data compression rate (S4). After the data recording iscompleted, the CPU operates a servo control circuit to rewrite a tableof contents (TOC) data to record data indicating the data compressionrate of the newly recorded data (S5).

[0022]FIG. 3 shows a flowchart of an operation processing with referenceto the CPU, while reproducing data which is recorded by the proceduredescribed in FIG. 2. After a multi-layered optical disk which has M datalayers, wherein M is an integer greater than 1, is loaded, the CPUoperates the servo control circuit to reproduce table of contents (TOC)data recorded in the multi-layered optical disk (S11). Then the CPUstores the reproduced TOC data in a memory (S 12). When the CPU receivesan operator's signal to reproduce certain data from the optical disk(S13), the CPU refers to the TOC data stored in the memory to identifythe data compression rate of the selected data (S14). Then the CPUoperates the routing switch to transmit a readout signal of the selecteddata to a determined encoding circuit in order to decompress theselected data (S15). After all of these procedures are completed, thedata reproduction is started.

[0023] Although the invention has been particularly shown and described,it is contemplated that various changes and modification may be madewithout departing from the scope of the invention as set forth in thefollowing claims.

What is claimed is:
 1. An optical disk recording and reproducing methodcomprising the steps of: receiving an operator's signal to record a dataon a multi-layered optical disk at indicated data compression rate;accessing to a read-in region to record the data; operating a routingcircuit to transmit the data to data compressing means which compressesthe data at the indicated data compression rate; recording the data atthe indicated data compression rate, and on the indicated region;rewriting a total of contents (TOC) data to record data about the datacompression rate of the newly recorded data; reproducing the TOC datarecorded in the multi-layered optical disk; storing the reproduced TOCdata in a memory; receiving the operator's signal to reproduce the datarecorded in the multi-layered optical disk; referring the TOC datastored in the memory to identify the data compression rate of the data;and operating a routing circuit to transmit readout signal of the datato data decompressing means which decompresses the data from theindicated data compression rate to a standardized bit rate of datasignal.
 2. An optical disk recording and reproducing method comprisingthe steps of: receiving an operator's signal to record a data on amulti-layered optical disk at indicated data compression rate; accessingto a read-in region to record the data; operating a routing circuit totransmit the data to data compressing means which compresses the data atthe indicated data compression rate; recording the data at the indicateddata compression rate, and on the indicated region; rewriting a total ofcontents (TOC) data to record data about the data compression rate ofthe newly recorded data; reproducing the TOC data recorded in themulti-layered optical disk; storing the reproduced TOC data in a memory;receiving the operator's signal to reproduce at least two datacontinuously, which are recorded in the multi-layered optical disk;referring the TOC data stored in the memory to identify data compressionrate and position of read-in region of all of the specified data;operating a routing circuit to transmit readout signal of the firstspecified data to data decompressing means which decompresses the firstspecified data from the indicated data compression rate to astandardized bit rate of data signal; accessing to read-in region of thefirst specified data by modulating pickup driving means according toidentified position of read-in region of the first specified data;reproducing the first specified data; operating a routing circuit totransmit readout signal of the next specified data to data decompressingmeans which decompresses the next specified data from the indicated datacompression rate to a standardized bit rate of data signal; accessing toread-in region of the next specified data by modulating pickup drivingmeans according to identified position of read-in region of the nextspecified data; and reproducing the next specified data.